PLoS Neglected Tropical Diseases最新文献

Background: The global epidemics of cholera, a virulent enteric infection, pose a serious threat to public health and socio-economics. The disease's rapid spread and high mortality have led to heavy casualties, along with disruptions to production, rising healthcare burdens and impaired economic exchanges.

Methods: Based on cholera historical and environmental data, Mann-Kendall test, wavelet analysis, hotspot analysis, epidemics center of gravity, and structural equation modeling were employed to investigate the spatial and temporal distribution pattern and formation mechanism of cholera epidemics in Hubei Province during the period of 1949-2020.

Results: Based on existing historical monitoring records. Temporally, high incidence occurred in the 1980s and 1990s, with summer and autumn being the dominant seasons. Three fluctuation cycles were identified: 29 years, 19 years, and 8 years. Spatially, 71 counties and districts were cumulatively affected, with Wuhan and Xianning serving as the primary hotspots. The epidemics was distributed along rivers and lakes, and its center of gravity shifted southward and westward over time. Mechanistically, cholera epidemics were the result of the combined effects of natural, disaster, and human factors. Population density and summer temperatures were the direct factors driving the spread of cholera epidemics, while river networks formed the basic environmental background that facilitated transmission. Natural environmental factors such as drought and flood disasters, elevation, and precipitation, as well as human environmental factors including road networks and economic conditions, could not only directly drive the spread of epidemics but also regulate epidemics development through indirect pathways. The coupling effects of various factors across different spatiotemporal scales jointly shaped the unique spatiotemporal distribution and evolutionary characteristics of cholera epidemics.

Conclusion/significance: This study helped to reveal the spatiotemporal patterns and formation mechanisms of regional cholera epidemics, filled the gap in cholera research in Hubei Province, and provided a reference for cholera prevention and control in areas with dense rivers and lakes.

Infections with soil transmitted helminths (STHs) are highly prevalent in humans living in the intertropical region. While, in most cases, STHs can establish chronic infections, the dynamics of the infection can be altered when other parasites exploit the same host. These changes can have consequences in terms of the health of the host, the epidemiology of the disease (e.g., the duration of the infection and the inter-host transmission success) and the fitness of the parasite. Here, we investigated if the coinfection with Plasmodium yoelii alters the dynamics (fecundity and with-host persistence) of the murine nematode Heligmosomoides polygyrus. We found that, compared to single infected mice, coinfected hosts excreted more worm eggs, while the worm biomass in the intestine did not differ between single infected and coinfected mice. Moreover, the increase in egg excretion was also observed when Plasmodium infected hosts that had been harboring the nematode during the past four weeks (i.e., when the population size of adult worms can only decrease due to mortality). Therefore, the enhanced shedding of eggs reflects a plastic adjustment of worm fecundity to the environment provided by a coinfected host. This plastic response was modulated by the host Th2 immunity, as coinfection inhibited IL-4 and IL-13 gene expression, plasma levels of IL-5 and IL-13, and the expansion of GATA-3+ CD4+ T cells in the spleen. In agreement with this, experimentally neutralizing IL-13 with monoclonal antibodies reproduced the results observed in coinfected mice (an increase in egg excretion), while the administration of recombinant IL-13 reduced egg shedding. Interestingly, coinfection extended the patent period of Heligmosomoides polygyrus (longer within-host persistence); moreover, a higher cumulative number of eggs was excreted, up to 99 days post-infection, in coinfected hosts. Although the gene expression of Th2 cytokines was lower at day 99 p.i., coinfected mice still had a downregulated expression compared to single infected hosts. These results offer a proof of concept that coinfection with Plasmodium has the potential to affect the epidemiology of STHs by increasing the number of eggs excreted over the whole infectious period and maintaining a larger environmental reservoir of transmissible stages.

Background: The World Health Organization (WHO) has emphasised the need for innovative diagnostic tools to support the control and elimination of neglected tropical diseases (NTDs). Microscopy-based diagnostics, the current standard, rely on trained technicians for labour-intensive processes, posing logistical challenges in the low-resource settings where NTDs are most prevalent. This study describes the technical details of an artificial intelligence-powered digital pathology (AI-DP) platform designed to support large-scale deworming programs for two NTDs, alongside its analytical performance and user experience in laboratory and field settings.

Methodology/principal findings: The AI-DP platform integrates electronic data capture tools, whole-slide imaging scanners, onboard AI analysis, and result verification software to automate microscopy-based screening. Targeting soil-transmitted helminthiasis (STH) and intestinal schistosomiasis (SCH) as initial use cases, the system was deployed in Ethiopia and Uganda, scanning 951 Kato-Katz (KK) thick smears containing 43,919 verified helminth eggs. Using 5-fold cross-validation, precision/recall/average precision were 95.4%/91.7%/97.1% for Ascaris lumbricoides, 95.9%/86.7%/94.8% for Trichuris trichiura, 84.6%/86.6%/91.4% for hookworm, and 89.1%/79.1%/89.2% for Schistosoma mansoni. Feedback from 14 field users across 30 real-world scenarios indicated the AI-DP platform's improved usability, particularly in hardware portability and software interfaces, though the average scan time of 12.5 minutes per smear was identified as a limitation.

Conclusions/significance: The AI-DP platform demonstrates potential as a tool for efficient monitoring and evaluation of STH and SCH control programs by providing near-real-time data with quality controls. However, further validation studies are needed to assess its clinical diagnostic performance, field usability, and cost-effectiveness in large-scale STH and SCH deworming programs. Given that the platform also provides a pipeline for any microscopy-based diagnosis, its potential for other NTDs also needs further attention.

Indonesia has the highest dengue burden in Southeast Asia, with 488 of 514 districts reporting cases annually across its 17,000-island archipelago. Despite this substantial burden, spatiotemporal transmission patterns remain poorly characterised. We analysed province-level dengue surveillance data (2010-2024) from Indonesia's Ministry of Health alongside local and regional climate variables to characterise heterogeneity in dengue periodicity and identify provinces where climate-based early warning may be feasible. Using wavelet phase analysis, dynamic time warping clustering, and distributed lag non-linear models, we examined relationships between climate and dengue incidence across 34 provinces. A systematic west-to-east gradient in dengue wave timing was identified, with Northern Sumatran provinces peaking earlier than other provinces, aligning with Australian-Asian monsoon progression. This gradient was robust in western Indonesia (Spearman ρ = 0.7 between longitude and phase lag) but weakened in eastern provinces. Multi-annual outbreak peaks (2015-2016, 2023-2024) coincided with strong El Niño events, with mean incidence during strong El Niño years was 96% higher than other years. The Indian Ocean Dipole showed no significant association. Phase coherence analysis identified 18 provinces where precipitation-dengue timing was sufficiently consistent (coherence ≥0.85) for potential early warning applications and DLNM confirmed significant dose-response associations in 11 of these. Indonesia's dengue-climate relationships exhibit structured heterogeneity that precludes uniform national prediction approaches but may enable province-specific early warning in high-coherence areas. A two-tier system combining ENSO monitoring for strategic preparedness with local climate monitoring for tactical intervention timing could improve outbreak response across Indonesia's diverse epidemiological landscapes.

Background: Chikungunya virus (CHIKV) can induce severe neurological manifestations in children. Investigating the role of the viral load (VL) in the blood and cerebrospinal fluid (CSF) could be of interest in understanding the mechanisms that mediate severity. This study aimed to analyze the characteristics of neurological manifestations of CHIKV in young patients at diagnosis and follow-up, with a particular focus on the potential relation between the severity of neurological involvement and the VL in the CSF and blood.

Methodology/principal findings: We conducted an observational longitudinal retrospective single-center study during the Chikungunya outbreak of 2014 on the French Caribbean Island of Martinique. We included children (excluding newborns) requiring lumbar puncture and who had positive CHIKV RT-PCR in the blood. Blood and CSF VL were assessed, and sociodemographic, clinical and biological characteristics were recorded. Among 651 children with a positive CHIKV RT-PCR in the blood; 86 were included, of whom 84 had positive RT-PCR in the CSF. Seven children developed probable encephalitis. Neurological manifestations were deemed severe in eight patients (9.3%), intermediate in 11 (12.8%) and non-severe in 67 (77.9%). Mean VL was 9.8 log in blood and 4.9 log in CSF. While mean blood and CSF VL were significantly higher in children aged <1 year, there was no significant association between blood and CSF VL and neurological severity. An initial follow-up carried out on 20 children one to six months after infection, showed good recovery. Additionally, 45 children underwent a neurology consultation 4 years later, of whom 8 (17.8%) presented with neurodevelopmental impairment.

Conclusion: Our results suggest that the CHIKV can invade the CNS at a high level during the acute phase of infection, but does not seem to be associated with the severity of neurological manifestations in children at the acute phase or with long-term cognitive development.

Hookworms are intestinal parasitic nematodes that chronically infect ~500 million people. How hookworms successfully overcome host protective mechanisms is unclear, but it may involve hookworm proteins that digest host tissues, or counteract the host's immune system, or both. To find such proteins in the zoonotic hookworm Ancylostoma ceylanicum, we used mass spectrometry to identify 565 genes encoding excreted-secreted (ES) proteins from adults, and used RNA-seq to identify genes expressed both in young adults (12 days post-infection) and in intestinal and non-intestinal tissues dissected from mature adults (19 days post-infection), infecting hamster hosts that either had normal immune systems or were immunosuppressed by dexamethasone. In adult A. ceylanicum, we observed 1,670 and 1,196 genes with intestine- and non-intestine-biased expression, respectively. Comparing hookworm gene activity in normal versus immunosuppressed hosts, we observed almost no changes of gene activity in 12-day young adults or non-intestinal 19-day adult tissues. However, in intestinal 19-day adult tissues, we observed 1,951 positively immunoregulated genes, and 137 genes that were negatively immunoregulated. Thus, immunoregulation was observed primarily in mature adult hookworm intestine directly exposed to host blood. Of positively immunoregulated intestinal genes, 50.1% (5.3-fold over background) also had male-biased expression, suggesting that male and female A. ceylanicum have different responses to the host immune system. We observed 153 ES genes showing positive immunoregulation in 19-day adult intestine, which disproportionately encoded CAP, ASPR, astacin, TIMP, TIL, ShK, and SCVP proteins, and that were enriched for ES gene orthologs in the dog hookworm Ancylostoma caninum, the human hookworm Necator americanus, or the related sheep parasite Haemonchus contortus. Such a mixture of rapidly evolving and conserved genes could comprise virulence factors enabling infection, provide new targets for vaccines against hookworm, and aid in developing therapies for immune-mediated diseases.

Background: In HLA-B*13:01-positive multibacillary (MB) leprosy patients, dapsone-containing multidrug therapy (MDT) carries a high risk of dapsone hypersensitivity syndrome (DHS). Alternative regimens (dapsone-free) are adopted, but their long-term efficacy compared with standard MDT in HLA-B*13:01-negative patients remains inadequately characterized.

Methodology: This retrospective cohort study analyzed MB patients (2015-2023) from the National Leprosy Prevention and Control Management Information System (LEPMIS) with ≥1-year follow-up. Primary outcomes (cure/relapse rates, bacterial index (BI), leprosy reactions, and disability progression) and secondary outcomes (adverse events and treatment duration) were compared between HLA-B*13:01-positive patients receiving alternative therapy (rifampicin + clofazimine ± clarithromycin/ofloxacin/minocycline) and negative patients receiving standard MDT (rifampicin + clofazimine + dapsone).

Findings: Among the 271 enrolled MB patients (120 HLA-B*13:01-positive, 151 negative), alternative therapy showed comparable efficacy to standard MDT in cure rates (67.6% vs. 65.8% at Year 5), the rate of BI decline (89.92% vs. 95.11% at Year 5), smear negativity rates (71.43% vs. 75.00% at Year 5) and relapse rates (0.46 vs. 0.20 per 100 person-years). Kaplan-Meier survival functions revealed no significant differences in leprosy reactions or disability progression. Additionally, alternative therapy demonstrated comparable safety to MDT (1.67% vs. 2.65%, P = 0.70).

Conclusions: In our study, dapsone-free alternative regimens demonstrated comparable clinical efficacy and safety to standard MDT in MB patients, providing a viable option for HLA-B*13:01 carriers. These findings, limited by the observational design and regimen heterogeneity, warrant further investigation in prospective trials.

Global pandemic interventions have reshaped host-virus dynamics, potentially altering the evolution of endemic pathogens. Here, we report accelerated genomic evolution of human coronavirus OC43 (HCoV-OC43)-a close relative of pandemic-associated coronaviruses-following recent worldwide epidemiological shifts. Bayesian analysis of longitudinal surveillance data revealed a 3.76-fold increase (8.9403 × 10 ⁻ ⁴ nucleotide substitutions/site/year, 95% HPD: 4.9075 × 10 ⁻ ⁴, 1.3053 × 10 ⁻ ³) in the spike gene substitution rate of the currently dominant genotype K post-2020. Positively selected mutations were mainly located in the spike protein, and some colocalize with antigenic epitopes. Crucially, structural modeling demonstrated that broadly neutralizing antibodies targeting conserved stem-helix (S2P6) and fusion-peptide (COV44-62/79, 76E1) epitopes of high-pathogenicity betacoronaviruses cross-bind HCoV-OC43 spike protein, establishing a mechanistic basis for immune-driven selection. These findings suggest that population-level immune imprinting may play a potential driving role in mutations within key domains of HCoV-OC43, although further validation is required. Sustained co-surveillance of co-circulating coronaviruses is imperative to anticipate emergent variants with altered pathogenicity.

Naja kaouthia, or the monocled cobra, is one of the most medically important snakes in Thailand, responsible for approximately 17% of snakebite cases. Conventional horse-derived antivenoms are lifesaving, yet they may trigger severe allergic reactions and exhibit batch to batch variability. Nanobodies (VHH) are promising alternatives as recombinant antivenoms having demonstrated the ability to neutralize snake venom both in vitro and in vivo. However, a major challenge in developing them is the diverse and complex composition of snake venoms, which requires therapies capable of targeting multiple toxins. To address this, we developed a bispecific VHH that simultaneously targets the two main toxins in N. kaouthia venoms, α-neurotoxin (αNTX) and phospholipase A2 (PLA2), fused to a human IgG Fc domain (bispecific VHH-Fc), which was selected to prolong serum half-life and reduce the immunogenicity risks associated with animal-derived antivenoms. The bispecific VHH-Fc, along with two monospecific nanobodies (VHH-αNTX-Fc and VHH-PLA2-Fc), was expressed in Chinese hamster ovary (CHO) cells and purified from culture supernatant after 5-6 days. Immunoblotting confirmed the successful expression and Fc fusion of these constructs, as detected by anti-human IgG-Fc antibodies conjugated to horseradish peroxidase (HRP). Importantly, antigen-binding assays demonstrated that the bispecific VHH-Fc exhibited the the strongest binding signal to crude N. kaouthia venom compared to the monospecific nanobodies. In in vivo murine neutralization assays, the bispecific VHH-Fc showing higher survival than equine-derived antivenom (33%) and comparable efficacy to a VHH-Fc cocktail under the tested conditions. Complete protection was achieved at higher doses. These results demonstrate that the bispecific VHH-Fc can be efficiently produced in a mammalian expression system and possesses strong binding and neutralizing activity against N. kaouthia venom under the defined experimental conditions. Our findings support the bispecific VHH-Fc as a promising next-generation therapeutic candidate for the treatment of snakebite envenoming, while highlighting the importance of integrating binding and functional assays when evaluating antibody efficacy.

Pathogenic Leptospira species can survive and thrive in a wide range of environments. Distinct environments expose the bacteria to different temperatures, osmolarities, and amounts and sources of nutrition. However, leptospires are mostly cultured in a laboratory setting under in vitro conditions that do not reflect natural environments. This constraint on laboratory cultures limits the applicability of in vitro studies to the understanding of even simple pathogenic processes. Here we report, investigate, and identify a medium and conditions that mimic the host environment during leptospirosis infection, expanding the available in vitro tools to evaluate leptospiral pathogenesis. We quantified genome-wide transcription of pathogenic Leptospira interrogans cultured in different in vitro media compositions and conditions-EMJH at 29 °C and DMEM, EMEM, and HAN at 37 °C and 5% CO2. Using EMJH as standard, we compared gene expression in these compositions to genome-wide transcription gathered in a host environment: whole blood (WB) of hamsters after infection with pathogenic leptospires. Leptospires cultured in DMEM and EMEM media shared 40% and 47% of all differentially expressed genes (DEGs) of leptospires present within WB (FDR < 0.01), while leptospires cultured in HAN media only shared 20% of DEGs with those from WB. Furthermore, gene and pathway expression of leptospires cultured on DMEM and EMEM media exhibited a better correlation with leptospires grown in WB, including promoting expression of a similar leptospiral lipid A profile to the one identified directly in host tissues. Taken together, these results indicate that commercial cell-culture media EMEM or DMEM are better surrogates for in vivo pathogenic studies than EMJH or HAN media in Leptospira. These alternative culture conditions, using media that are a standard supply worldwide, provide a reproducible and cost-effective approach that can accelerate research investigation and reduce the number of animal infections necessary for basic research of leptospirosis.